In fluidic angular rate sensors, a stream of a suitable fluid, such as an inert gas, is pressurized and passed through a nozzle. The stream of fluid is directed by the nozzle toward a pair of temperature sensitive resistive elements which are differentially cooled by the stream whenever the stream is diverted (such as by Coriolis forces that are encountered during angular rotation of the sensor). The differential cooling provides a measurable differential signal across the resistive elements which is proportional to the angular rate of turn of the sensor. Such fluidic rate sensors are generally accurate in a plane of sensitivity which is generally defined as being perpendicular to the plane in which the resistive elements lie. Fluidic angular rate sensors are typified by those disclosed in U.S. Pat. Nos. 3,587,328, to Schuemann, 3,626,765 to Moore, and 4,020,700 to Lopiccolo et al.
Such prior art angular rate sensors utilize a nozzle having a circular opening The circular opening provides a laminar gas stream having a parabolic velocity profile As is well known, the shape of the velocity profile of the gas stream is defined as a function of the distance from the center of the opening. The gas stream moves more quickly at its center and moves more slowly near its sides thereby defining the parabolic shape of the profile. A portion of each leg of the profile is roughly linear. Each linear portion impinges upon one of the resistive elements throughout the normal operating range of the rate sensor. If the portions of the profile that impinge upon the resistive elements are nonlinear, measurement of the differential cooling of the elements may not provide an accurate measurement of the angular rate of turn of the sensor. If the angular rate sensor of the above described prior art are rotated at greater than about 500.degree.-600.degree. per second, the Coriolis forces tends to bend the profile such that a nonlinear portion of the profile impinges on one or both of the resistive elements. An inaccurate measurement of the angular rate of turn of the sensor may then result.